A serial rapist who pleaded guilty to the cold-case sex slaying of a 19-year-old Bellevue woman 34 years ago on Friday was given a minimum 14½-year prison sentence, but the judge made it clear he hopes Michael Halgren spends the rest of his life in prison.

The maximum sentence for the April 23, 1980, strangulation of Susan Barbara Lowe is life, and King County Superior Court Judge Roger Rogoff said that would be his preferred sentence.

Halgren, 58, has admitted to raping more than 20 women. In 2002, he was deemed a “sexually violent predator” after a civil trial and sent to the Special Commitment Center (SCC) on McNeil Island. In 2012, Halgren’s DNA was collected and matched to semen found on Lowe’s body, according to charging papers.

Prosecutors say Halgren raped Lowe and strangled her with a pair of pantyhose.

Halgren was originally charged with first-degree murder, but last month pleaded guilty to second-degree murder because DNA evidence in the case had degraded over time. Should he ever be released from prison, Halgren will return to the SCC, the judge was told.

Senior Deputy Prosecutor Kristin Richardson also noted that at the time of Lowe’s death, crime-scene investigators and officials from the medical examiner’s office didn’t routinely wear gloves and likely left their DNA at the scene as well.

Richardson asked the judge to sentence Halgren to at least 13½ years, while defense attorney John Ostermann sought a minimum sentence of just over 12½ years.

Ostermann said Halgren wanted to spare Lowe’s family the pain of a lengthy and exhausting trial and added that his client — who is diabetic and in poor health — hoped to spend his final years at the SCC, which is a secure treatment facility for violent sex offenders. Its residents are considered patients, not inmates, and have more freedom.

But Rogoff, noting the coldblooded nature of Lowe’s death, disagreed.

“It is the court’s opinion that Mr. Halgren should spend his life in prison rather than in treatment,” he said, handing down a minimum sentence that is likely to ensure parole — and a return to the SCC — won’t be possible until Halgren is in his 80s.

Halgren, 58, will be required to serve his minimum sentence before going before the state Indeterminate Sentence Review Board, which can add up to five years at a time to a defendant’s sentence — up to life.

Halgren declined to address the court on Friday.

According to court documents, Lowe had told her roommate she planned a quiet night at home watching a Seattle SuperSonics game, according to charging documents. Neighbors later reported hearing a loud knock on Lowe’s door, followed by a banging noise and a muffled scream, but nobody called police, the charges say.

The next morning, Lowe’s roommate found her in bed, nude, strangled with a pair of her own pantyhose, according to the charges. Although Halgren and Lowe were strangers, he lived a few blocks away from her apartment and both frequented the same Eastside bowling alley, the charges say.

In 2006, Johnson hand-delivered the case file on Lowe’s homicide to King County prosecutors, who had just created a new unit to review unsolved cold cases.

It was the unit’s first case and there’s been “great dedication to this case,” Richardson said, noting Lowe — a beautiful young woman who “was finding her way in the world” — died a horrible death.

For Johnson, Halgren’s sentencing “ends just a long process for all the officers I know personally who were part of the case.

“After 34 years, they get an end result and the family does, too,” Johnson said outside the courtroom.

He credited Wade with helping solve the case after she collected DNA samples from Halgren and several dozen other SCC residents who hadn’t had their DNA entered into a national database when they were released from prison.